To make textile bobbins, it is necessary in principle on the one hand to make the bobbin rotate and on the other to traverse the traveling yarn, which is being wound onto the rotating bobbin, along the bobbin axis. If the yarn is traversed very slowly, a bobbin with highly parallel windings is created. If such a bobbin is meant to have a relatively large volume and to have flat face ends disposed substantially at right angles to the bobbin axis, then boundary disks are required on both ends of the package. These boundary disks are not necessary if the yarn is traversed fast enough to produce a cross winding. High winding speeds thus require a very high traversing rate as well.
Drive means such as belts, oriented parallel to the bobbin axis, can be used for this purpose. European Patent Disclosure EP 0 311 827 A2 describes one such yarn guide in which the belt is driven by means of a microprocessor-controlled stepper motor. High traversing speeds can be attained and the yarn guide can be controlled relatively precisely.
So-called shogging rollers are also very widely used to create the traversing motions; in high-speed bobbin winders, they often simultaneously utilized to provide the circumferential drive for the cheese. However, the laying angle dictated is always the same, regardless of the bobbin fullness, and at certain rpm ratios between the bobbin and the drive roller, so-called ribbon windings occur, which later present considerable unwinding problems. The prior art therefore describes many so-called ribbon breaking methods.
To create a predetermined winding pattern, such as a precision or graduated precision winding, the bobbin must be driven separately from the yarn guide. This can be done, among other ways, by spacing the aforementioned shogging roller apart from the takeup bobbin, which is driven separately. As a rule, a yarn guide then slides in the shogging groove. This system has disadvantages because of inertia.
So-called finger yarn guides have also long been known (for instance from published, examined German Patent Application DE AS 11 31 575 and published, unexamined German Patent Application DE OS 15 60 360), in which a finger- or fork-like yarn guide is pivotable about an axis disposed substantially perpendicular to the takeup bobbin axis. Instead of the conventional mechanical drive mechanisms described therein, electromechanical drive mechanisms have meanwhile been proposed for these fork-like yarn guides of the kind suggested for instance in European Patent Application EP 0 808 791 A2 or in European Application EP 0 838 442 A1, which representatively describe this basic type of drive. However, these references merely mention that these drive means are electric motors. It can be assumed that either the rotary motion of the motor is converted into a pivoting motion of the yarn guide finger, via gear means that increase the inertia of regulation, or else a motor is used that drives the yarn guide finger directly, and in the case of a stepper motor generates the desired pivoting angle via a predeterminable number of steps. Given the high speed and the high direction-reversal frequency, stepping errors can occur, which then lead to a permanent shifting of the drive mechanism and consequently to winding flaws.
In conventional electric motors, such as electronically commutated motors, it is also difficult on the one hand to generate a required high moment at the turning points but on the other to keep the mass of the rotor, which executes only a pivoting motion, small enough that the resultant mass inertia does not further increase the required moment.